Yea I think its all about giving Locke this false sense of control. Locke has been so desperate to gain some because he could never attain any with his father and now here is Ben this pseduo father/control figure and Locke desperately wants to get some of this control. Locke wants to feel like he is the important one on the island and Ben is completely aware of that, which is where manipulation comes into play. But**** Ben does need Locke as well because he sees that Locke was healed on the island and he has not healed yet.

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